It is generally helpful to drivers if they are made aware of changes in driving conditions ahead of time. For example, in rural areas it is common for the speed limit on roads, such as state highways or county roads, in sparsely populated areas to be set at a maximum allowed speed, such as 55 to 70 miles per hour (MPH). When the road passes through a more populated area, such as a small town, the speed limit may drop suddenly to a slower speed, such as 25 to 45 MPH, for vehicles passing through the town before rising again to 55 to 70 MPH after the town. Other rapid changes in speed may occur when a driver approaches an intersection, a stop sign, a traffic light, a tollbooth, a school or hospital zone, a railroad crossing, or the like. Occasionally, signs, such as “speed zone ahead,” may warn driver of the upcoming change in road conditions, but usually no other warning is available. If the driver is distracted, drowsy, or unfamiliar with the road he is traveling on, he may be surprised by the sudden change in road conditions. As a result, the driver may be unintentionally operating his vehicle at an unsafe or illegal speed. It would be safer if the driver was provided with additional warnings of upcoming changes in road conditions.
In addition to the permanent or static road conditions noted above, such as intersections, traffic signs or lights, or special speed zones, road conditions may also change due to temporary or dynamic changes, such as accidents, construction, heavy rush-hour traffic, special-events, weather, recurring events, or the like. No warning signs are available for many of these temporary or dynamic changes to road conditions since they are unscheduled and unexpected. As a result, drivers may come upon these road conditions without notice and with little time to reduce speed or otherwise adapt to the changed conditions. It would be safer if drivers also had some warning of these temporary and dynamic changes in road conditions. Furthermore, some dynamic events like scheduled sporting events, school opening/closing times, bus stops, etc. may be scheduled and, perhaps, expected, though it would still be advantageous and desirable to provide appropriate warnings to drivers.
Current vehicle navigation systems may provide warnings to drivers of upcoming route changes, such as upcoming turns, or provide directions to drivers to stay on route, such as instructions to stay or veer left or right where a selected route intersects multiple lanes or roads. Current vehicle navigation systems may also provide drivers with information regarding a current location, such as a street name. Other than these route-specific warnings and directions and current-location information, current vehicle navigation systems do not provide the driver with information regarding upcoming road conditions, road limitations or traffic conditions.